Ozonized gas contains a predetermined concentration of ozone. The ozonized gas is powerful in deodorizing and bactericidal effects, and is used at a water treatment plant and the like. Among methods for generating ozonized gas industrially, usually used is a method whereby a source gas is circulated in the micro space formed between an grounding electrode and a dielectric discharge tube, and a high frequency electric field is applied to the micro space, and then silent electric discharge is generated (for example, Patent Documents 1-7). Ozone is generated in the micro space from oxygen or a source gas containing some oxygen, by the electric discharge energy of the silent electric discharge. The grounding electrode is made up of a metal tube of stainless steel and others. The dielectric discharge tube consists of a cylindrical glass and the like, which includes a high voltage electrode inside. The high voltage electrode is a thin film, which is formed of metal, such as aluminum and the like, on the inner surface of the dielectric discharge tube, by thermal spraying and others. Generally, an ozone generator produces ozone at a higher efficiency, when the generator is operated at a high gas pressure. Accordingly, the grounding electrode, the dielectric discharge tube, and others are stored in a high pressure tank.
For example, in the ozone generator according to Patent Document 1, the high voltage electrode is a conductive thin film, which is made by using a method, such as coating of the conductive coating material. The dielectric discharge tube includes a left end which is sealed. The right end of the tube, which is arranged at an ozonized gas outflow side, has an open structure. The open end of the dielectric discharge tube is at the ozonized gas outflow side and sealed with a lid. The lid prevents the diffusion of the ozonized gas into the inner side of the dielectric discharge tube, and restrains the corrosion of the high voltage electrode by ozone. In the ozone generator according to Patent Document 2, a clearance gap between the dielectric discharge tube and the lid is sealed with fillers like adhesive cement and others, or is sealed with inorganic adhesive. In a low temperature plasma generator according to Patent Document 3, a rod like conductor (0.6-4.5 mm in diameter) is inserted into the inside of a ceramic dielectric body (1-5 mm in diameter) with a cylindrical conformation. The ceramic dielectric body and the rod like conductor are sealed at both ends, by fusion bonding with glass or joining with adhesives or other methods.
In the ozone generator according to Patent Document 4, the ozone generator is in a configuration where a dielectric discharge tube includes an open port at a source gas inflow side and a closed end at the opposing ozonized gas outflow side. A gas circulation plug is installed in the open end of the dielectric discharge tube, which is arranged at the source gas inflow side. A small hole is opened in the gas circulation plug. When the ozone generator makes an emergency stop, the source gas stops its flow. The ozone generated at a discharging space spreads into the source gas inflow side of the dielectric discharge tube. Only a small hole is opened in the gas circulation plug, and then, ozone does not intrude into the dielectric discharge tube. Moreover, since the small hole is provided in the gas circulation plug, an excessive pressure is not applied to the dielectric discharge tube at regular times. Accordingly, the ozone generator is high in the reliability of the dielectric discharge tube.